In this investigation, FeS2 thin films were synthesized by spray pyrolysis technique on glass substrates. The films were annealed at 400 ºC and 450ºC in air for a period of 1 hour. The optical characterizations of the as deposited and annealed films were carried out using UVÂVIS transmittance spectroscopy in the wavelength range 400Â900 nm. The results show that in the visible region the transmittance of the films decreases as the annealing temperature increases to 450ºC. The reverse is the case with the reflectance as it was observed to be increased in the same region. The result also shows that the absorption coefficient, extinction coefficient, real and imaginary parts of dielectric constant are tending to increase with the increasing of annealing temperature. Further analysis shows that the films have high optical conductivity about 4.06-6.20 x 1014S-1. The refractive index was found to be 4.38-5.14. The foregoing desirable propertiesmake the FeS2 to be a promising material for the fabrication of solar cells and optoelectronic devices.